module.exports = function(steps, modulesInfo, addSteps, copy) {
  // Genates a CLI string for the current sequence
  function toCliString() {
    var cliStringSteps = '"', cliOptions = {};
    for (var step in this.steps) {
      var name = (typeof this.steps[step].options !== 'undefined') ? this.steps[step].options.name : this.steps[step].name;
      if (name !== 'load-image'){
        cliStringSteps += `${name} `;
      }
      for (var inp in modulesInfo(name).inputs) {
        cliOptions[inp] = this.steps[step].options[inp];
      }
    }
    cliStringSteps = cliStringSteps.substr(0, cliStringSteps.length - 1) + '"';
    return `sequencer -i [PATH] -s ${cliStringSteps} -d '${JSON.stringify(cliOptions)}'`;
  }

  // Checks if input is a string of comma separated module names
  function detectStringSyntax(str) {
    let result = (str.includes(',') || str.includes('{')) ? true : false;
    return result;
  }

  // Parses input string and returns array of module names
  function parseStringSyntax(str) {
    let stringifiedNames = str.replace(/\s/g, '');
    let moduleNames = stringifiedNames.split(',');
    return moduleNames;
  }

  // imports string of comma separated module names to sequencer steps
  function stringToSteps(str) {
    let sequencer = this;
    let names = [];
    if (this.name != 'ImageSequencer')
      sequencer = this.sequencer;
    if (detectStringSyntax(str))
      names = stringToJSON(str);
    names.forEach(function eachStep(stepObj) {
      sequencer.addSteps(stepObj.name, stepObj.options);
    });
  }

  // Strigifies the current sequence
  function toString(step) {
    if (step) {
      return stepToString(step);
    } else {
      return copy(this.steps.map(stepToString).slice(1).join(','));
    }
  }

  // Stringifies one step of the sequence
  function stepToString(step) {
    var arg = (step.name) ? step.name : step.options.name;
    let inputs = modulesInfo(arg).inputs || {}, op = {};

    for (let input in inputs) {

      if (!!step.options[input] && step.options[input] != inputs[input].default) {
        op[input] = step.options[input];
        op[input] = encodeURIComponent(op[input]);
      }

    }

    var configurations = Object.keys(op).map(key => key + ':' + op[key]).join('|');
    return `${arg}{${configurations}}`;
  }

  // exports the current sequence as an array of JSON steps
  function toJSON() {
    return this.stringToJSON(this.toString());
  }

  // Coverts stringified sequence into an array of JSON steps
  function stringToJSON(str) {
    let steps;
    if (detectStringSyntax(str))
      steps = parseStringSyntax(str);
    else
      steps = [str];
    return steps.map(stringToJSONstep);
  }

  // Converts one stringified step into JSON
  function stringToJSONstep(str) {
    var bracesStrings;
    if (str.includes('{'))
      if (str.includes('(') && str.indexOf('(') < str.indexOf('{'))
        bracesStrings = ['(', ')'];
      else
        bracesStrings = ['{', '}'];
    else
      bracesStrings = ['(', ')'];

    if (str.indexOf(bracesStrings[0]) === -1) { // if there are no settings specified
      var moduleName = str.substr(0);
      stepSettings = '';
    } else {
      var moduleName = str.substr(0, str.indexOf(bracesStrings[0]));
      stepSettings = str.slice(str.indexOf(bracesStrings[0]) + 1, -1);
    }

    stepSettings = stepSettings.split('|').reduce(function formatSettings(accumulator, current, i) {
      var settingName = current.substr(0, current.indexOf(':')),
        settingValue = current.substr(current.indexOf(':') + 1);
      settingValue = settingValue.replace(/^\(/, ''); // strip () at start/end
      settingValue = settingValue.replace(/^\{/, '').replace(/\}$/, ''); // strip {} at start/end
      settingValue = decodeURIComponent(settingValue);
      current = [
        settingName,
        settingValue
      ];
      if (settingName) accumulator[settingName] = settingValue;
      return accumulator;
    }, {});

    return {
      name: moduleName,
      options: stepSettings
    };
  }

  // imports a string into the sequencer steps
  function importString(str) {
    let sequencer = this;
    if (this.name != 'ImageSequencer')
      sequencer = this.sequencer;
    var stepsFromString = stringToJSON(str);
    stepsFromString.forEach(function eachStep(stepObj) {
      sequencer.addSteps(stepObj.name, stepObj.options);
    });
  }

  // imports a array of JSON steps into the sequencer steps
  function importJSON(obj) {
    let sequencer = this;
    if (this.name != 'ImageSequencer')
      sequencer = this.sequencer;
    obj.forEach(function eachStep(stepObj) {
      sequencer.addSteps(stepObj.name, stepObj.options);
    });
  }

  return {
    toCliString: toCliString,
    detectStringSyntax: detectStringSyntax,
    parseStringSyntax: parseStringSyntax,
    stringToSteps: stringToSteps,
    toString: toString,
    stepToString: stepToString,
    toJSON: toJSON,
    stringToJSON: stringToJSON,
    stringToJSONstep: stringToJSONstep,
    importString: importString,
    importJSON: importJSON
  };
};